In addition to a liquid fuel volume, vehicle fuel tanks also contain a gas volume, which is usually filled by fuel vapors and/or air. Temperature fluctuations lead to corresponding internal-pressure fluctuations in the fuel tank. Excess pressures which occur have to be reduced, but emission regulations mean that fuel vapors must not escape into the atmosphere. The pressure is therefore reduced by bleeding fuel vapors into a canister containing activated carbon through a vent line, which leads from the fuel tank. Such carbon canisters are typically vented to an operating engine to purge from the canisters the fuel vapors, which are burned in the combustion process of the engine. Presently, such carbon canisters are typically remotely located from the fuel tank, such as under a frame of a vehicle. This approach requires providing space under a vehicle frame to accommodate the carbon canister, separately assembling the carbon canister to the vehicle, and routing relatively long vent lines to and from the carbon canister.
A more recent approach involves attaching a separate carbon canister to an exterior surface on a top wall of the fuel tank. The carbon canister extends outside of the fuel tank, wherein one surface of the carbon canister is exposed to the atmosphere and an opposite surface is exposed to the fuel in the fuel tank. Unfortunately, however, this approach still involves providing space on the vehicle to accommodate the protruding carbon canister.